Fixed deopt reasons in TaggedToI.

Every DeoptimizeIf should be preceded by a RecordComment explaining
the reason. In the long run, the reason should be an argument of
DeoptimizeIf, but we're not there yet.

On x87, things are a bit ugly due to some pushing/popping, so if
somebody feels inclined to improve this: Feel free. Probably the right
approach would be reloading instead of the push/pop horror.

Another thing is our inconsistent handling of the "done" continuation
of deferred code on the various platforms, I made tiny changes on the
way, but this should better be unified somehow, with all those
micro-optimizations removed.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/578583002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23996 ce2b1a6d-e550-0410-aec6-3dcde31c8c00